Dynamo electric machine



Oct, 29, A G. G. I ANDl'sY 2,019,082

DYNAIO ELECTRIC CHINE Filed Nov. 193s 9% uu.. y by? ATTORNEY.;

Patented Oct. 29, 1935 UNITED STATES DYNAMO ELECTRIC MACHINE George G. Landis, Cleveland, Ohio, assigner to The Lincoln Electric Company Application November 29, 193s, semi Nd. 698,857

5 Claims.

This application is a continuation in part oi' my co-pending application Ser. No. 640,390, led October 31, 1932, now Patent No. 1,962,692, dated June 12, 1934.

This invention relates, as indicated, to dynamo electric machines and more particularly, to electric current generators adapted particularly for use in the generation of electric current used in the arc welding process.

It is a principal object of my invention to provide a welding current generator, a construction which may be readily and accurately adjusted for varying arc requirements.

It is a further object of my invention to provide a generator in which the recovery time is greatly reduced so as to cause the voltage and currentto more closely follow the requirement of the arc.

It is likewise an object of my invention to provide means in association with the generator and responsive to changes in the amount of welding current whereby during any such changes, the energization of the series ileld or the voltage of the arcing circuit, or both, may be either increased or decreased.

Other objects of my invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention, then consists of the means hereinafter fully. described and particularly pointed out in the claims, the annexed drawing and the following description setting forth in detail certain means and modes illustrating, however. several of various ways in 'which the principle of the invention may be used.

In said annexed'drawing:

g. 1 is a schematic wiring diagram oi' a generator constructed in accordance with the principles of this invention showing particularly the series neld windings and the means for controlling or varying the strength of the series tleld; Fig. 2 is similar to a portion of the schematic diagram illustrated in Fig. 1, showing a different arrangement for varying the strength of the series tleld and Figs. 3 to 12, both inclusive, are similar to Fig. 2. showing alternative forms of the means for varying the strength of the series ileld.

As previously indicated, the present invention relates particularly to welding current generators l and more speciflcally to the means for varying 4ducedtoamininzlum.

(Cl. T11- 242) In my above identiiied `co-pendng application there is disclosed an arrangement oi the windings and associated mechanism in the generator whereby the transformer action between the series and shunt or separately excited iield wind- 5 ings of the generator is practically eliminated. In such application there is also disclosed the use of an inductive shunt for/varying the strength of the series eld and it is to the use of such induc tive shunt for the purpose described that this 10 invention particularly relates.

In Figure l of the drawing there lsillustrated a weldin current generator including a diagrammatical vrepresented armature I with associated variable shunt or separately excited ileld windings 16 2 and variable series ileld windings 3. Inthe armature circuit which includes the arc l there may also be included interpole windings 5 as is usually the case in machines oi the character un der consideration. A variable resistance I in se 20 ries with the shunt or separately excited illd winding 2 may be employed for the purpose of regulating and controlling the strength ot such eid. A shunt including a variable resistance l is connected around the series neld winding 3 for 25 the purpose of regulating and controlling .the strength of the series held. In the ensuing description, it will be assumed that the series Md is wound diierentially with respect to the shunt and/or separately excitedwlnding and it molds! 30 also be kept in mind that in an actual CWI-w1 tion the series windings 3, as well as the shunt or separately excited windings 2, will probably be' split up into sections arranged o'n the several poles of the machine. However. whensuch is 35 the case, the several sections of the series winding will be wound cumulatively with to each other and differentially with resct to the windings 2. v

'Ihe oonstruction'illustrated in Figure 1 is rep 40 resentative of the-arrangements heretofore employed in the prior art welding current generators as taught to the art by Mr. A. H. Homrlghaus in his Patent No. 1,238,406, dated August-28, 1917.

When the strength oi the series field is varied 45 or controlled by means of' a resistance shunt therearound. such arrangement has certain disadvantages which are particularly pronounced and objectionable at the time the are In an arrangement such as is illustrated in Pig. l, 50 the impedance oi the series winding I opposing any sudden change in the'amount oi' currmt iiow therethrough 'causes the surge oi' current occurring at the time the arc is struck to substantially all flow through the resistance shunt'l. There I6 is, therefore, a certain time lag imm the instant the arc is struck until the distribution of current iiow between the series winding 3 and the shunt l reaches equilibrium. 'I'his time interval seriously interferes with the recovery rate of the machine and it is to the solution of this problem that the present invention, as exemplified in Figs. 2 to 12 presently to be described, pertains.

In Figs. 2 to 12 showing different modifications of the means for varying the strength of the series field, the amature I and its associated shunt or separately excited ileld winding 2 have not been included for purposes oi convenience. It is to be understood, however, that the portions of the circuits illustrated in these ngures include the armature circuit of the generator. It should alsobe pointed out that it is within the contemplation of my invention to variously arrange the series ileld windings and the interpole winding with respect to the arc and armature, i. e., the leads from the series circuit might well be connected to the opposite poles from those shown in Figure 2 and furthermore, the arc in the series circuit might be positioned in any other desired relation to the remaining windings than that illustrated in the drawing without departing from the principles of this invention.

Referring now more speciilcally to Fig. 2, the arrangement illustrated herein includes an inductive variable resistance shunt l connected around the series winding 3 for the purpose of varying the strength of the series feld. The'shunt l includes a variable resistance unit l and a reactance winding III. When an arrangement such as is illustrated in Fig. 2 is employed, and when the arc is struck closing the armature circuit, the inductive reactance of the winding I0 will immediately eiect the propex current distribution between the series eld winding 3A and the shunt I. When a construction such as is illustrated in Fig. 2 is employed, the time of recovery of the machine isY materially reduced over the time of recovery of a machine having a winding such as illustrated in Fig. l.

The proportional relationship between the inductive reactance of the windings 3 and III, of course, determines the proportional amountoi the arc current which will ilow through the series vwinding 3. Obviously, in order to be effective toaccomplish the desired ends, the inductivereactance oi th'e winding In should be equal to at least a substantial amount of the inductive reactance oi the series winding 3. It has been found that the inductive reactance of the shunt 8, in order to at least partially accomplish the desired results, should amount to at least 20% of the inductive reactance of the eld winding 3.

The variable resistance 3' in the shunt 8 may. oi course, be adjusted similarly to the variable resistance 'I illustrated in Figure 1, whereby there may be adjustments for suitable ranges of automatic regulation of the arcing circuit through a given no-load voltage as taught in the previously identiiied Patent No. 1,238,406 to Homrighaus.

In Figure 3, the variable inductive resistance shunt around the series eld winding 3 consists of a winding II in which there'is combined resistance and inductance and the effectiveness of the shunt is varied by cutting out successive turns oi the winding II which is effective to simultaneously reduce the reactance and resistance oi the shunt. y'

In Figures 4, 5, and 6, there are illustrated three generally similar methods of and means for varying the strength of the series held. 'Ihe principal difference between the arrangements illustrated in these last-named figures and the arrangements illustrated in Figures 2 and 3 is that all oi the resistance and reactance units are in the circuit at all times.' 3

In Figure 4 a variable resistance I2 is connected in parallel with the series eld winding 3 and an adjustable contact I3 associated with one side of the line may, when moved along the resistance unit I2, variously proportion the amounts oi such resistance which are respectively in series and parallel with the series winding 3.

In Figure 5, the arrangement is somewhat similar to Figures 4 and 2, i. e., the shunt generally indicated at I4 includes a reactance unit I5 and a variable resistance unit I6, these units being connected in series with respect to each other and in parallel with respect to the series winding 3.

In Fig. 6, similarly as in previously described Fig. 3, the shunt generally indicated at Il consists of combined resistance and reactance-winding IB which is connected in parallel with the series winding 3. The movable lead I9 oi the armature circuit of the generator may be moved along the winding I8 to vary theproportional amounts oi such winding' which are respectively in sexies and in parallel with the ileld winding 3.

In Fig. 7, the shunt illustrated for the purpose of .varying the strength of the series eld includes a resistance unit 2II which, depending upon the setting of the movable lead 2 I, will be wholly or in part either in series or parallel with the series winding 3. In Fig. 8 the shunt, as illustrated in Fig. '1, is modiiled by the inclusion therein of a reactance winding 2i. which has a resistance unit 22 connected in series therewith. In the arrangement illustrated in this gure,

movement of the lead 23 to selected points along 40 the resistance unit 22 determines the proportional amounts oi such resistance which are respectively in series and parallel with the series winding 3, while the'reactance winding 2| is, at all times, connected in parallel with the field 45 winding.

In Fig. 9 there is shown a modiilcation oi the disclosure in Fig. 8 along the lines indicated in previously described Figures 3 and 6. The principaldiilerence between the operation oi' the ap- 50 parat'us illustrated in Fig. 9 and that illustrated.

in Fig. 8 is that as the resistance in parallel with the series ileld 3 is reduced by an upward movement oi the lead 24, the reactance ot the winding 25 in parallel with the series winding 3 is likewise 55 reduced.

A further arrangement for varying the operating characteristics of the machine is illustrated in Fig. l0, wherein the series ileld is separated into two parts 26 and 2l, respectively, which may imv have an equal or-unequal number oitums and which are diil'erentially compound-wound, i. e., cumulatlvely with respect to each other and ditferentially with respect to the shunt or separately excited windings 2, and may be on the same or g5 different pole pieces oi themachine. These two elds are arranged in parallel and are connected by means of a bridging variable resistance. Movement of the lead 29 oi the welding circuit along the resistance 28 will atl'ect the amount oi 7o current ilowing in the respective windings 26 and 21 and when such windings have a diilerent number of turns, the ampere turns strength oi' the series eld may be varied without a change in the amount of welding current ilow. u

The arrangement illustrated in Fig. 11 is similar to that illustrated in Figure 10. change being made, however. in the inclusion of. a reactance winding 30 in series with the bridging resistance 8| and in Figure 12, the bridgingresistance and reactance windings are combined into a single unit I2 in the-manner explained in connection with the description of previous Figures 3, 6, and 9.

From the foregoing explanation of the invention as illustrated in Figs. 2 to 12, it will be evident that a principal feature of the invention as particularly illustrated in Figs. 2, 3, 5, 6, and 8 to i2 is the employment of an inductance coil in the diverter circuit or shunt for the purpose of limiting the flow of transient currents in this circuit, causing such transients to flow through the series iield, thereby speeding up the change in flux ln the magnetic circuit of the generator and improving its performance. The desired results are, therefore. obtained in the previously.

ing and the shunt at the instant the arc is struck.

Ii the impedance of the shunt is only equal to a small proportional amount of the impedance of the series eld winding, then the major portion of the welding current at the instant the arc is struck will flow through the shunt. If the impedance of the shunt is equal to the impedance of the series ileld winding, then the weld current ilow, at the instant the are is struck, will be evenly distributed between the two branches. If, however, the impedance of the shunt is considerably greater than the impedance of the series field winding, then at the instant the are is struck, the'major proportion of the welding current will iow through the series field winding.

After the lapse of a suflicient time interval for the distribution oi' welding current between the series field winding and shunt branches of the circuit to reach equilibrium, the respective amounts of current ilow through these branches will depend upon the resistance of such branches and this distribution is, o'f course, controlledby a setting of the variable resistance inthe shunt. From the foregoing, it will be apparent to those familiar with the art that by a proper proportioning of the reactance'in the series eld and in the shunt therearound, the amount of welding current which will iiow through the series field at the instant the arc is struck may be controlled to any extent in order to provide the mostdesirable operating characteristics for the machine.

In addition to the illustrations of the several modifications illustrated in the drawing and hereinbeiore described, it is to be understood, however. that there may be further modifications and particularly other combinations of the illustrated schemes inorder to secure different and perhaps more refined control over the strength of the series field and the manner ,in which the same responds to and follows the current flow in the arc. For instance, as illustrated in my aforementioned co-pending application, the several shunts herein described may b connected around ments of the arc.

' sistance winding, and means for simultaneously only a portion of the series eld winding `and again, the number of turns oi the series eld winding which are in series with the arcand/or in parallel with the shunt may be varied by bringing out taps from the series field windings at 5 selected points.

I wish to particularly point out that it is a feature of this invention to vary the strength of the series eld by relatively small increments. which may be accomplished by any of the means '10 and in the several modes above pointed out and described. Such variation by relatively small increments makes it possible to adjust the output of the machine very closely to the exact require- As previously indicated, it will be'apparent to 15 those familiar with the art that there may be various combinations and sub-combinations of the illustrated and described arrangements for varying the strength of the series eld and it is 20 within the contemplation of my invention that such variations, combinations and sub-combinations ma'y be made in order to suit the particular requirements, such as the particular operating characteristics of the machine, as well as cost 25 and facility of manufacture.

It is tobe understood that the various arrangements illustrated and described herein for varying the strength of the series field in a welding current generator are particularly useful when used 30 in conjunction with a machine in which the windings are arranged as illustrated in the several tlgures of the drawing of my aforesaidPatent No. 1,962,692, and specific reference is here made to such figures as included within the disclosure of 35 this application.

Other modes.of applying the principle if any linvention may be employed instead of the one explained, change being made as regards the means herein disclosed, provided those stated by any of the following claims or theirl equivalent o be employed.

I, therefore, particularly point out and distinctly claim as my invention:

1. An electric arc welding system including a welding current generator and Aan arc circuit, which arc circuit includes a plurality of parallel circuits, one of said parallel circuits containing a series eld winding of the generator, another of said parallel circuits containing an inductive reand oppositely varying the impedance of said parallel circuits.

2. An electric arc welding system including a welding current generator and an arc circuit, which circuit includes a series eld winding of the generator and an inductive resistance winding connected in parallel therewith and means for simultaneously varying in opposite directions respectively the impedance of the arcing current circuit through said series field winding and through said inductive resistance winding.

3. An electric arc welding'system including a welding current generator and an arc circuit, which circuit includes a series eld winding of the generator and an inductive resistance winding connected in parallel therewith and means for simultaneously varying in opposite directions respectively the inductive reactance of the arcing current circuit through said series eld winding and through said inductive resistance winding.

4. An electric arc welding system including a welding current generator and an arc circuit, which circuit includes a series field winding of the generator and an inductive resistance winding u connected in parallel therewith und means (or simultaneously varying in opposite directions xespectively the resistance of the ming current circuit through said series neld winding md through 5 said inductive resistance winding without mate,-

ria-liy varying the inductive xetnnce of auch 5. An electric arc welding system including a welding current generator and an are circuit.

respectivelytheimxaucdcneeotthe|.rcixmcurx'enlz4 wenn through um mies nem winding andthe 'resistance ci' the nrcins current circuit through' said inductive resistance windinz. v

GEORGE G. LANDIS. 

